<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<style>
		/* id选择器 */
		#para1{
			text-align: center;
			color: red;
		}
		/*class选择器*/
		.center{
			text-align: center;
		}
	</style>
	<body>
		
		<p id="para1">
			aaaaa
		</p>
		
		<p class="center">
			qqqqq
		</p>
		
	</body>
</html>